1. Field of the Invention
This invention relates to a motion simulating apparatus. More specifically, a motion simulator according to the present invention comprises a base support connected to a motion platform by a plurality of hinged or scissor legs in combination with at least one actuator for moving the motion platform relative the base support.
2. Prior Art
Many different types and designs of motion simulators have been proposed and constructed. The number of degrees of freedom and degrees of motion being simulated place limitations on the structural arrangement of the design.
Historically, the effects of providing realistic simulated motion to supplement other sensory inputs during dynamic training, entertainment and similar applications has been thoroughly documented. Motion is achieved through the use of mechanical means by the use of electro-mechanical systems designed to achieve the particular affect desired depending on the application. All such devices are limited in their ability to simulate motion ideally due primarily to physical excursion limits, mechanical hardware capability, design considerations and computer modeling/hardware limitations.
The basic design goals of motion simulation are to provide: 1) large excursion motion for improved simulation and "wash out" effects; 2) minimal friction in component parts for better feel and stability; 3) minimal backlash (lost motion), also for better feel and stability; 4) compact size in terms of both foot print and minimal height to the motion platform; and 5) minimal weight for motion platform and active actuator components. It needs to be understood that there are only two primary effects experienced by persons riding on a motion platform. They are the forces associated with acceleration and gravity. These two effects are manipulated by the programmer in conjunction with other sensory stimuli (usually visual in nature) to obtain the illusion of true motion. In reality, only actual initial acceleration and simulated sustained acceleration effects are possible. Clearly the intent is to provide improved mechanical designs which allow for improved simulation quality.
All rigid bodies in Euclidean three (3) dimensional space are capable of six (6) degrees of freedom (i.e. three translation (X,Y,Z) and three rotation (Yaw, Pitch, Roll)). Depending on the application, it is necessary to provide a motion simulation device with one or more of these motions in various combinations. Clearly, the more independent motions available, usually the better the simulation.
A true six (6) degree-of-freedom (DOF) system as described b K. L. Cappel (U.S. Pat. No. Re. 27,051 reissued 1971) is the dominant motion simulation design presently in use. Other devices having fewer degrees of motion have been proposed and built, however, the designs have resulted in complex and expensive equipment with limited excursion capability and constrained motion. This constrained motion results in a degree of motion and not a true degree of freedom, and hence, yields compromised motion resulting in a lower quality of simulation.
Although ideal simulation requires six (6) DOF, it is well documented that three (3) degree-of-motion simulation utilizing two (2) rotational motions (Pitch, Roll) and one translational motion (Z-heave) can provide excellent capability for a wide range of physical applications. Ideally, the three (3) axes of motion would be independent, making the system a true three (3) DOF platform, however, motion is often constrained because of kinematic limits resulting non-independent motion. This limitation clearly impacts the degree of fidelity of the simulated motion and hence realism for the passenger.
Previous motion system kinematics have precluded realistic motion due to the severity of constraint placed on a particular axis. Characteristically, attempts to minimize inter-dependency between axes has resulted in non-symmetrical designs having a multitude of special parts, custom designs and manufacturing, and, an excessive degree of complexity resulting in higher initial, operating and maintenance costs.
In addition, for example, previous motion systems have tended to produce false motion cues and hence compromise simulation. Such false cues can, in a training scenario, result in negative training. This is the result of excessive constraints placed on a particular axis of motion where the motions of two axes are not sufficiently uncoupled. The level of non-connectedness is crucial to good simulation regardless of the number of axes of motion.
Ideally, a completely uncoupled system results in a true degrees-of-freedom system. True independent motion is difficult to achieve in simple mechanisms. In the past, three (3) degrees of motion systems (Pitch, Roll, Z) have been strongly coupled kinematic relationships such that movement along one axis resulted in strongly noticeable motion in another axis, to the point where training or simulation effects were nullified or negative. Motion systems of the prior art typically have limited excursion capability, highly coupled motion axes and complex physical construction.